I played an X-Wing on 4, Skyscraper on 2 and Multi-coloring on 7, not knowing to what extent, if any, these contributed to the solution. Overlapping URs, Type 1 on 23 and Type 4 on 29 set r1c8<>23 and r1c5<>2. These exposed an XY-Wing on 239; r1c8, r2c5<>9.